Patent GB-155823-A (GB)
Title: Improvements in or relating to telephone systems
Filed: 1920-12-09
Abstract: 155,823. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Wicks, J.). Dec. 20, 1919, [Convention date]. Automatic and semi-automatic exchange systems.-In a system in which trunk connections are obtained by an operator, the operator is provided with means for setting up a separate automatic connection to the calling line and for releasing the switches over which the call originally reached her. This arrangement prevents the calling subscriber from escaping the trunk charge by giving his own number incorrectly, but does not put him to the trouble of hanging up his receiver and waiting for a back call. Local calls are made by means of line switches C, Fig. 4, first and second sectors E, F and connectors H in the usual way. A subscriber A desiring a trunk connection operates the selector E to its tenth level to find an idle jack J at the trunk operator's position. The operator obtains the wanted trunk connection by way of the cord O and jack J<2>, and then withdraws the plug from jack J, inserts it in jack J<1>, and connects herself to the calling subscriber by special trunk selectors E<1>, F<1> and a connector H of the series which serves also for local calls. Since the calling subscriber's receiver is off its hook, the operator gets a busy signal. She then presses a key associated with the jack J to release the switches C, E over which the call originally reached her, and the release of these switches momentarily removes the busy potertial from the calling subscriber's test terminals, enabling the connector H to seize the calling line. In order that the operator may be able, if necessary, to ring the calling subscriber, in spite of his receiver being off its hook, a ring- ing-generator is associated with the selector F<1> and is arranged to be brought into circuit by the depression of a ringing-key in the cord O. Detailed operation. The switches C, E, Fig. 3, operate in known manner to connect a calling subscriber A to an idle jack J, Fig 1. The energization of relay 91 lights a lamp L, and the operator plugs a cord-circuit O into the jack J and throws her listening-key K<2> to enquire the wanted connection, which she obtains by way of the jack J<2>. She then removes the answering- plug from jack J and inserts it in the jack J<1> of a selector E<1> (the idle condition of which is indicated by the non-illumination of a lamp L<1>) and operates her impulse sender S<1> to call the calling subscriber. Selectors E<1>, Fig. 1, and F<1>, Fig. 2. The circuit operations during the vertical and rotary movements of these selectors are practically the same as in the standard selector E, Fig. 3, only that the line relay 115, Fig. 1, instead of being controlled as usual over the two talking-wires, is controlled over a circuit through the bush of the jack J<1>, and the line relay 205, Fig. 2, is controlled over an extension of the same circuit through a front contact of the switching-relay 114 and a fourth wiper 141. During the rotary movement of the selector F' a relay 207 in the circuit of the rotary magnet energizes a relay 203, which locks itself up. As soon as connection has been made to an idle connector H, Fig. 3, the switching relay 204 is energized in known manner and extends a control circuit to the connector through a fourth wiper 261, at the same time bridging a battery feed relay 202 across the outgoing trunk through the right-hand windings of the repeater R. Connector H, Fig. 3. The connector H, which, in the case of local calls, is controlled in the usual way over the trunk conductors 273, 275, is controlled by the trunking operator over the wire 277 and the fourth wiper 261 of the selector F'. The line relay 301 (upper winding) is energized in this circuit in series with relay 305. Relay 302, energized by relay 301, grounds the test wire 274, to mark the connector busy to second selectors F of the local series and energizes relay 304, which locks up the relay 305. The resistance of relay 304, which is connected to the test wire 278, is low enough to mark the connector busy to the trunking selectors F<1>. The two remaining sets of impulses are repeated by relay 205 to relay 301, and conirol the vertical and rotary movements of the connector in known manner. Busy signal. The relay 308, which is energized in parallel with the rotary magnet, connects the test wiper 381 to relay 307, and since the test terminal 384 of subscriber A is grounded at contact 93, Fig. 1, the relay 307 is energized, and, upon the relapse of relay 308, locks itself to the wiper 381 through a circuit prepared by the relay 305. (In the case of a local call to a busy line, relay 307 would have locked itself to ground at the contact 325). Relay 307 connects the tonedevice Q over wire 279 to the lower winding of relay 202 Fig. 2, giving the operator an audible signal and energizing relay 202, which energizes relay 201, which opens the trunk circuit 148, 152 so as to de-energize relay 94 and extinguish the lamp L<2>. Release of the switches C, E. This is effected by the operator pressing a key K, Fig. 1, associated with the jack J, so as to disconnect ground from the holding-wire 87. The disappearance of earth potential from the terminal 384, Fig. 3, unlocks the relay 307, which closes a circuit through relays 309 and 14 before the latter relay has had time to de-energize. Relay 309 locks itself up, completes the talking-circuit to the subscriber's line, and grounds the test wiper 381. The subscriber A is now fed with current through relay 202, Fig. 2. Automatic ringing. If the line of subscriber A. should test idle, the subscriber having hung up his receiver, the operator can ring him by pressing her key K<2>, Fig. 1, which transmits alternating current to relay 200, Fig. 2, which unlocks relay 203, which de-energizes relay 304, Fig. 3, which connects the ringer G<1> to the subscriber's line. A tell-tale portion of the ringing-current reaches the operator through the repeater R. When the subscriber A lifts down his receiver, relay 203 is energized in the line circuit and locks itself up again, energizing relay 304, which cuts out the ringer G<1>. Non-automatic ringing. The operator, by means of her key K<2>, can also ring the subscriber A when his receiver is off its hook. In these circumstances the relay 201 is already energized, putting an additional lock on the relay 203 and preparing a circuit for relay 209, so that the effect of the energization of relay 200, when the ringing key K<2> is pressed, is not to unlock relay 203, as described in the previous paragraph, but to energize relay 209, which connects a ringer G<2> to line. Release. When the subscriber A hangs up his receiver, the relapse of the feed relay 202 deenergizes relay 201, which bridges the trunk circuit 148, 152, energizing relay 94, Fig. 1, which lights the lamp L<2>. The operator withdraws the plug from the jack J<1>, and the opening of the grounded sleeve circuit releases the iswitches E<1>, F<1>, H.